Considering a lot of Sunday teams considering Saturday football removing the lower Sat or Sun team becomes quite realistic in a few seasons I think
Edit: KNVB is moving towards a 'weekend' competition instead of the Saturday/Sunday divide, so your idea is closer to reality than some think in this thread.

Probably not without some editing.
Other question, is it possible to have a team that doesn't have any youth intake? So it would only be able to pick up cast offs (or is that blocked by the transfer embargo?)

I always thought the problem was in the Confederations Cup, as they need qualifiers from all the continents and it will not work without at least one of the continental championship. Myth debunked by you it seems.

Not the best of titles, but I'll try to explain what I am after.
Whenever I am working on edits, one of the things that bugs me, is the way the pre-game editor orders which items you have used. Let's say, you are changing the team for quite a lot of players. So for the first three players you have a new club. If you look at the order these clubs are now shown in the search screen you will see they are shown from oldest to newest. Nothing wrong with that, unless you end up with a list of items longer than your screen. I now end up scrolling through the whole list to an item I used just seconds before.... I just it, show it top of the list instead
Wouldn't it be so much more logical going from newest to oldest?
If anyone knows how to do this in one of the XML files, please let me know.

A sort of Communist Champions League, right?
You make a new International Club Competition, call it whatever you want and select Continent World. Next you make the International Club Competition, pick your Nations that deliver your teams and you're done.
Picking your nations might be interesting, the 15 Soviet teams, Bulgaria, Romania, Poland, Hungary, Czech Republic and Slovakia are a certainty. East Germany doesn't exist anymore, so how do you pick a team from the East German area is an interesting question. Albania and the Former Yugoslav countries are also communist, but at various moments turned their back to the Soviets.
Of course, that's all up to you.

With regards to point 2, there is an easy fix. The screen where you pick your Nations is ordered alphabetically. Despite not showing, your deleted countries are still there. If you change, say, Croatia to ZzzCroatia and do the same to all other countries you deleted the screen will work properly again.

You will need to keep all nations in the game for FM19. The Iron Curtain mod was build in FM16, which doesn't mind removing nations.
It is possible that the Nations League or something is set up around that date. It very much sounds like the date the ties are decided for an international competition that starts somewhere the summer afterwards.

That would work similar to the Nations League, so that's a yes.
If you build a international competition you have the option in a round to pick the form of League format. The Concacaf uses it for instance.

Simple, remove the continent and then move all data (Cities, Clubs, Players and Local Regions) to the nation of your choice and integrate the extra teams into the competition. Ok, slightly more work, but if you're not planning to do very precisely you can rebuild Czechoslovakia in about half an hour or less.